Delivery of oxygen and oxygen-enriched air to the respiratory tract of a patient can result in discomfort to the patient, especially when the air is delivered over an extended period of time. Delivery of air having relatively low absolute humidity can also result in respiratory irritation.
When heating and humidifying a breathing gas for breathing through a nasal cannula, any cooling in the nasal cannula may lead to excessive condensation within the nasal cannula. When excessive condensation is present within the nasal cannula, drops of liquid water may subsequently be delivered to the patient's nose.